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A modified process yields lower levels
of internal porosity for solder joints produced
in reduced-gravity environments.
The process incorporates both alternative
materials and a modified procedure.
The process provides the necessary
cleaning action to enable effective bonding
of the applied solder alloy with the
materials to be joined.

The modified process incorporates a
commercially available liquid flux that is
applied to the solder joint before heating
with the soldering iron. It is subsequently
heated with the soldering iron to activate
the cleaning action of the flux and to
evaporate most of the flux, followed by
application of solder alloy in the form of
commercially available solid solder wire
(containing no flux). Continued heating
ensures adequate flow of the solder alloy
around and onto the materials to be
joined. The final step is withdrawal of the
soldering iron to allow alloy solidification
and cooling of the solder joint.

This method provides adequate cleaning
of contaminants by the flux agent
from the materials to be joined, but allows
dissipation of most of the flux agent prior
to application of the solder alloy. This significantly
reduces the amount of flux that
can be entrapped in the solder alloy that
would result in internal porosity.

This work was done by Kevin Watson of
Johnson Space Center; Peter Struk of Glenn
Research Center; and Richard Pettegrew,
Robert Downs, and Daniel Haylett of the
National Center for Microgravity Research. MSC-24023-1

This Brief includes a Technical Support Package (TSP).

Modified Process Reduces Porosity When Soldering In Reduced Gravity Environments (reference MSC-24023-1) is currently available for download from the TSP library.

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